Friday, 18 May 2012 01:55
May 18, 2012
A novel way of making cement could help drastically reduce the greenhouse gas emissions generated during the process, MIT's Technology Review reports.
Producing lime, the most important ingredient in cement mixtures, releases a significant amount of greenhouse gases into the atmosphere every year. Companies that specialize in crafting cement have long struggled to devise more efficient ways of generating lime, but their efforts have often stalled.
Researchers at George Washington University recently unveiled a proof of concept that would allow for the production of lime without many of the deleterious environmental consequences that result from conventional strategies. If the model proves viable, it could help revolutionize the cement industry, experts contend.
Cement production accounts for approximately six percent of all greenhouse gas emissions annually. Generating lime is by far the most carbon-intensive part of the process, according to the news provider. Such is true because of a number of factors, including the fact that firms routinely employ fossil fuels to heat limestone to exceedingly hot temperatures, often in excess of 1,500 degrees Celsius.
Replacing fossil fuels with renewable energy sources is complex, however, and would not necessarily address another intrinsic obstacle: to generate lime from limestone, which is calcium carbonate, it must be heated until carbon dioxide is released. Scientists at GW concentrated their engineering research on tweaking the traditional technique.
Instead of simply implementing solar cells to help power the reactions, the researchers developed a system that converts the resultant carbon dioxide into oxygen and either carbon or carbon monoxide. To achieve such an outcome, they engineered a scheme that employs both electrolysis and heat. What's more, they used a mixture of calcium carbonate and liquid lithium carbonate to increase its effectiveness.
The compound is molten around 900 degrees Celsius, a property that cut the amount of electricity needed in electrolysis, which in turn helps separate lime, according to the scientists. Aside from helping cut carbon emissions, the process also costs less than conventional methods, the researchers noted. PhysOrg reports that by introducing electrolysis into the process, scientists were ultimately able to change the reaction's byproducts.
"Electrolysis changes the product of the reaction of the limestone as it is converted to lime," Stuart Licht, a chemistry professor at GW, said in an interview with Phys Org. "Rather than producing carbon dioxide, it reduces the carbon dioxide [adds electrons] and produces only oxygen and graphite [which can be readily stored as solid carbon] or CO for fuels, plastics or pharmaceuticals. This is accomplished at low energy and high throughput."
Additionally, they contended that it could help significantly reduce projected greenhouse gas levels over the next few decades, especially as developing nations ratchet up their cement production as they undertake massive infrastructure projects.
"Although the process itself is entirely new, the individual components are already in place," said Licht. "Solar energy can be used to efficiently make products without carbon dioxide, and at solar energy efficiencies higher than in photovoltaics."
The researchers recently published their findings in Chemical Communications.